redisson的outofDirectMemory异常

我正试图通过Redisson学习Redis。下面是我使用多线程插入redis的代码

package redisson

import java.io.File;
import java.util.concurrent.atomic.AtomicInteger;
import org.redisson.Redisson;
import org.redisson.api.RBatch;
import org.redisson.api.RMap;
import org.redisson.api.RedissonClient;
import org.redisson.config.Config;


public class RedisTest extends Thread {

    static RMap<String, String> dMap = null;
    static RMap<String, String> wMap = null;
    static RMap<String, String> mMap = null;
    static RedissonClient redisson = null;

    public static void main(String[] args) throws Exception {

        Config config = Config.fromJSON(new File("C:\\Users\\neon-workspace\\RedisProject\\src\\main\\resources\\SingleNodeConfig.json"));
            RedissonClient redisson = Redisson.create(config);
            dMap = redisson.getMap("Daily");
            wMap = redisson.getMap("Weekly");
            mMap = redisson.getMap("Monthly");

            connectHbse(dMap,wMap,mMap,redisson);
            redisson.shutdown();

    }

    public static void connectHbse(RMap<String, String> dMap,RMap<String, String> wMap,RMap<String, String> mMap,RedissonClient redisson) {
        int totalSize=500000;
        int totalThread=2;
        int chunkSize = totalSize/totalThread;
        AtomicInteger total = new AtomicInteger(chunkSize);
        RedisTest test1[] = new RedisTest[totalThread];
        for (int i = 0; i < test1.length; i++) {
            test1[i] = new RedisTest(total,dMap,wMap,mMap,redisson);
            total.set(total.intValue()+chunkSize);
        }
        long t1 = System.currentTimeMillis();
        for (int i = 0; i < test1.length; i++) {
            test1[i].start();
        }
        try {
            for (int i = 0; i < test1.length; i++) {
                test1[i].join();
            }
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        System.out.println("Final Total Time Taken ::>>>>>>>>>>>>>>>>> " + ((System.currentTimeMillis() - t1))+"ms");
    }

    private AtomicInteger total = null;
    public RedisTest(AtomicInteger total,RMap<String, String> dMap,RMap<String, String> wMap,RMap<String, String> mMap,RedissonClient redisson) {
        this.total = new AtomicInteger(total.intValue());
        this.dMap = dMap;
        this.wMap = wMap;
        this.mMap = mMap;
        this.redisson = redisson;
    }

    public static int getRandomInteger(int maximum, int minimum) {
        return ((int) (Math.random() * (maximum - minimum))) + minimum;
    }

    public void run() {

        try {

            long t1 = System.currentTimeMillis();
            dMap.clear();
            wMap.clear();
            mMap.clear();
            RBatch batch = redisson.createBatch();

            for (;total.decrementAndGet()>=0;) {    
                String dvalue = ""+getRandomInteger(100,200);
                String wvalue = "" +getRandomInteger(200, 300);
                String mvalue = "" +getRandomInteger(300, 400);

                batch.getMap("Daily").fastPutAsync(""+total.get(), dvalue);
                batch.getMap("Weekly").fastPutAsync(""+total.get(), wvalue);
                batch.getMap("Monthly").fastPutAsync(""+total.get(), mvalue);

                    synchronized (total) {
                        if(total.get()%100==0)
                            System.out.println(total.get()+" Records in Seconds:::::" + ((System.currentTimeMillis() - t1))/1000);
                    }
            }
            batch.execute();

            System.out.println("Time Taken for completion::::: " + ((System.currentTimeMillis() - t1))+" by thread:::::"+Thread.currentThread().getName());
            System.out.println("Done !!!");
        } catch (Exception e) {
            System.out.println("Done !!!" + e.getMessage());
            e.printStackTrace();
        } finally {

        }
    }
}

但我有大约7Gb的可用内存。

---

有人能给我解释一下为什么会出现这种异常吗？

似乎我应该使用-Xmx为我的JVM实例提供更多的内存，它为我解决了这个问题

io.netty.handler.codec.EncoderException: io.netty.util.internal.OutOfDirectMemoryError: failed to allocate 16777216 byte(s) of direct memory (used: 939524096, max: 954466304)
    at io.netty.handler.codec.MessageToByteEncoder.write(MessageToByteEncoder.java:125)
    at org.redisson.client.handler.CommandBatchEncoder.write(CommandBatchEncoder.java:45)
    at io.netty.channel.AbstractChannelHandlerContext.invokeWrite0(AbstractChannelHandlerContext.java:738)
    ... 25 more
Caused by: io.netty.util.internal.OutOfDirectMemoryError: failed to allocate 16777216 byte(s) of direct memory (used: 939524096, max: 954466304)
    at io.netty.util.internal.PlatformDependent.incrementMemoryCounter(PlatformDependent.java:627)
    at io.netty.util.internal.PlatformDependent.allocateDirectNoCleaner(PlatformDependent.java:581)
    at io.netty.buffer.PoolArena$DirectArena.allocateDirect(PoolArena.java:764)
    at io.netty.buffer.PoolArena$DirectArena.newChunk(PoolArena.java:740)
    at io.netty.buffer.PoolArena.allocateNormal(PoolArena.java:244)
    at io.netty.buffer.PoolArena.allocate(PoolArena.java:226)
    at io.netty.buffer.PoolArena.reallocate(PoolArena.java:397)
    at io.netty.buffer.PooledByteBuf.capacity(PooledByteBuf.java:118)
    at io.netty.buffer.AbstractByteBuf.ensureWritable0(AbstractByteBuf.java:285)
    at io.netty.buffer.AbstractByteBuf.ensureWritable(AbstractByteBuf.java:265)
    at io.netty.buffer.AbstractByteBuf.writeBytes(AbstractByteBuf.java:1046)
    at io.netty.buffer.AbstractByteBuf.writeBytes(AbstractByteBuf.java:1054)
    at org.redisson.client.handler.CommandEncoder.writeArgument(CommandEncoder.java:169)
    at org.redisson.client.handler.CommandEncoder.encode(CommandEncoder.java:110)
    at org.redisson.client.handler.CommandBatchEncoder.encode(CommandBatchEncoder.java:52)
    at org.redisson.client.handler.CommandBatchEncoder.encode(CommandBatchEncoder.java:32)
    at io.netty.handler.codec.MessageToByteEncoder.write(MessageToByteEncoder.java:107)
    ... 27 more